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Right channel dropping out when adjusting selector switch on Marantz PM550dc

D

DirtyRecords

New Member
Hey everyone, long time lurker but first time poster on this forum.

I have some trouble with my Marantz PM550dc. The right channel keeps cutting out when the amplifier is running. When I adjust the selector switch, it can sometimes come back on for a certain period of time. Trying to put the selector switch ''between'' modes (such as between the phono MM2 and MM1 inputs) sometimes fixes the problem as well.

I already serviced this amplifier twice at a professional store and the problem comes back after about 3-6 months. Before spending another 150$, I was wondering if trying to clean the insides of the amplifier myself could fix the problem. When opened, the amp doesn't seem particularly dirty or corroded. Also, should I try using Deoxit D5 or F5 for this and where should I spray?

Also, any other switches, buttons, and equalizer mixers functions properly, including the left/right balance fader when the selector correctly plays both channels.

Here are some pictures of the selector switch and circuit board:
https://imgur.com/a/HAPxthy

Thanks for you help and input!
 
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Well, it can either be a dirty switch or a bad switch.
  1. The first thing to try is to spray some Deoxit D5 into the areas marked with the red arrows.
  2. Next, rotate the switch back and forth about 40-50 times to work it into the contacts.
  3. Let is sit overnight, then try it again tomorrow.
  4. If it doesn't help, let us know. :cool:
1689276779803.png

1689276883251.png
 
Solid detailed answer, this is also what I could gather from all those youtube restoration videos. Thanks for indicating specifically where to spray the D5. I'll try it and let you know how it goes!
 
dankik said:
Well, it can either be a dirty switch or a bad switch.
  1. The first thing to try is to spray some Deoxit D5 into the areas marked with the red arrows.
  2. Next, rotate the switch back and forth about 40-50 times to work it into the contacts.
  3. Let is sit overnight, then try it again tomorrow.
  4. If it doesn't help, let us know. :cool:
View attachment 2932494

View attachment 2932495
Click to expand...
Just wanted to let you know that this solution worked. Well, spraying D5 only in the selector switch didn't function; weirdly the channel only came back when I sprayed and played with the other switches at the bottom of the amp (EQ defeat, filters, mono, etc.). In any case, a thorough deoxit cleaning of all pots and switches brought the channel back. Thanks a lot for your help!
 
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